206 TRANSACTIONS OF THE [aPrR. 15, 
Besides the anorthoclase, a few crystals of the ordinary 
plagioclase type were observed. 
Augite occurs in poorly developed crystals or irregular grains, 
almost colorless and with no apparent pleochroism. It is 
mostly altered to hornblende, chlorite or epidote. In the 
strongly granophyric specimens the augite and other ferromag- 
nesian silicates are in very small amount. 
Brown hornblende. A pale brown hornblende, with a very 
high extinction angle, 25° maximum, occurs in moderate 
amount. It is in part at least secondary after augite, but some 
of it seems to show its own crystal outlines, and if so, may be 
considered original. Its pleochroism is: 
ownish yellow, 
O—pale reddish brown, 
pale vellowish brown, 
a>b>c. 
Green hornblende. This is in varying quantity, and appears 
to be in all cases paramorphic after augite and brown horn- 
blende. It has the usual colors and pleochroism of uralitic horn- 
blende, though its structure is almost compact. The stages in 
the alteration of the augite appear to be, 
1. Brown hornblende, 
2. Green hornblende, sometimes bleached before passing into 
3. Chlorite. 
Epidote occurs as an alteration product, but apparently not 
of this series; the conditions of its formation must have been 
different. In some sections no augite or brown hornblende is 
found, but only an aggregate of green hornblende, epidote and 
chlorite. 
Apatite is an abundant accessory, in the usual long prisms, 
which are rather more abundant in the quartz. 
Magnetite occurs in small irregular masses and is in part 
titaniferous. Pyrite is occasionally to be noticed. 
Zircon appears in every section examined in crystals of square 
cross section. In the concentrates these are seen to be made up 
of the unit prism and pyramid, rarely showing their edges in 
the slightest degree modified. This character of the crystals is 
much in contrast with the rather abundant zircons of the intru- 
sive granite-diorites of the Laurentian. The latter have the unit 
and second-order prism and unit pyramid much modified by de- 
velopment of several other faces, giving them a rounded outline, 
while the zircous of the soda-granite are sharp-edged and clean 
cut. The difference in character may perhaps be due to the con- 
ditions of solidifying, more probably to the chemical composi- 
tion of the magma. 
